The subject invention relates to a differential apparatus including an auxiliary input mechanism to control the wheel speed of a vehicle.
Conventional differential apparatuses for controlling the wheel speed of a vehicle are known in the art. Generally, a differential apparatus transmits a driving force from a vehicle engine to an output shaft or shafts of the vehicle. Ultimately this driving force is transmitted to the vehicle wheels, which are associated with the output shafts of the vehicle. The operating performance of the vehicle wheels is dependant on the amount of torque available at the wheels. Conventional differentials typically include an exclusive input for controlling the wheel speed of the vehicle. That is, the driving force from the vehicle engine is typically transmitted by a single pinion gear that is mounted to a drive shaft of the vehicle. The pinion gear operates as the exclusive input to the conventional differential apparatus.
As a result of this exclusive input, when such conventional differentials are applied particularly to a heavy vehicle having wheels or to a track-driven vehicle the amount of torque available at the wheels is affected. More specifically, if a wheel on a first side of the differential slips due to poor traction conditions, the torque available at a wheel on the other side of the differential can be no more than the torque that is developed at the wheel on the first side that is slipping due to the poor traction conditions. This is true regardless of the traction conditions at the wheel on the other side of the differential. That is, the torque that is developed at the wheel on the other side of the differential can be no more than the torque that is developed at the wheel on the first side even if satisfactory traction conditions are present at the wheel on the other side of the differential.
Furthermore, such conventional differential apparatuses limit the effectiveness of the vehicle because the output shafts are restricted to rotation in the same direction. As a result, it is not possible for the vehicle to pivot about a stationary position. That is, the vehicle cannot turn without progressing forward or backward to some degree. Pivoting about a stationary position is a critical and therefore desirable characteristic in the heavy vehicle or track-driven vehicle industries where these vehicles are frequently required to function in confined spaces.
All of these problems became particularly acute in differentials that utilize planetary transmissions.
Due to the inefficiencies identified in conventional differential apparatuses, it is desirable to implement a differential apparatus that incorporates an auxiliary input mechanism that enables different rotational speeds and different rotational directions of the output shafts of a vehicle to more effectively control the wheel speed and traction of a vehicle.